Standard plugin features

Download the plugin from GitHib. Now, let's take a look at the structure of the duallang plugin together. There are three files worth mentioning:

• version.php: This contains not only the version information of the plugin itself but also the minimum version of Moodle required to run it. It also, optionally, contains a list of dependencies. The following is a copy of the relevant code from our new plugin:

      $plugin->component = 'local_duallang'; 
      $plugin->release = 'alpha1'; 
      $plugin->version = 2016112300; 
      $plugin->requires = 2015030900; 
      $plugin->maturity = MATURITY_ALPHA; 
      $plugin->dependencies = array(); 

• lang/en/local_duallang.php: This contains the plugin's language strings. There is only one language string required for this basic plugin and that is the name of the plugin itself:

      $string['pluginname'] = 'Dual language string manager'; 

• classes/duallang_string_manager.php: This script contains the overridden implementation of the core_string_manager class, specifically, the get_string() function, which has been modified to construct a language string from both the UK English and the simplified Chinese Mandarin language packs:

      class duallang_string_manager extends 
      \core_string_manager_standard { 

          /** 
          * Implementation of the get_string() method to display both 
          simplified 
          * Chinese and UK English simultaneously. 
          * 
          * @param string $identifier the identifier of the string to 
          search for 
          * @param string $component the component the string is 
          provided by 
          * @paramstring|object|array $a optional data placeholder 
          * @param string $langmoodle translation language, null means 
          use 
          * current 
          * @return string 
          */ 
          public function get_string($identifier, $component = '', $a = 
          null, 
          $lang = null) { 

              $string = parent::get_string($identifier, $component, $a, 
              'en'); 

              $zh_cn = parent::get_string($identifier, $component, $a, 
              'zh_cn'); 

              if(strlen($zh_cn) > 0) { 
                  $string .= ' | ' . $zh_cn; 
              } 

              return $string; 
          } 
      } 

Note that in order to specifically load UK English and simplified Chinese, we simply call the method in the parent class (refer to the An objected-oriented philosophy section for some elaboration on the parent/child class relationship).

At the top of each PHP script, you will find a general comment header, important copyright, and optional version control information. You will also see the following line of code:

defined('MOODLE_INTERNAL') || die(); 

This prevents someone from outside of Moodle from accessing the PHP script. To install the plugin, we can either copy the files to Moodle's local folder or use Moodle's built-in plugin installer (for details, visit https://docs.moodle.org/31/en/Installing_plugins#Installing_via_uploaded_ZIP_file):

Once installed, we will also need to add a line to Moodle's config.php file (located in Moodle's root directory):

Return to Moodle's home page and you will now see the UK English and simplified Chinese Mandarin language strings displayed side by side: